1. Field
Embodiments of the invention relate to the field of audio speakers; and more specifically, to the construction of diaphragms for audio speakers.
2. Background
Audio speakers use electrical signals to produce air pressure waves which are perceived as sounds. Many audio speakers use a diaphragm that is movably suspended in a frame. The diaphragm is coupled to a voice coil that is suspended in a magnetic field. The electrical signals representing the sound flow through the voice coil and interact with the magnetic field. This causes the voice coil and the coupled diaphragm to oscillate in response to the electrical signal. The oscillation of the diaphragm produces air pressure waves.
It is desirable for the diaphragm to be stiff so that the diaphragm radiates as a piston as high in frequency as possible. Deformation of the diaphragm affects the efficiency and directivity of the loudspeaker. Diaphragms are generally thin plates and exhibit bending modes within the bandwidth of operation. Making the diaphragm stiff increases the frequency of bending modes. Ideally, the resonant frequency for the first bending mode will be well above the maximum audible frequency.
It is also desirable for the diaphragm to be lightweight. A heavier diaphragm requires more force from the voice coil to move the diaphragm. With a fixed force available, the lightness of the diaphragm is directly proportional to the efficiency of the loudspeaker. A lighter diaphragm reduces the amount of electrical energy that has to be supplied to the voice coil to reproduce a certain pressure. Thus a lighter diaphragm is particularly useful for compact, battery powered devices where it is desirable to minimize power consumption, size, and weight of an audio speaker.
Thus it would be desirable to provide a stiff, lightweight diaphragm for use in audio speakers.